A digital-to-analog converter (DAC) is a device that converts a digital code (e.g., a binary code) into an analog signal. A conventional DAC architecture uses a sequence of numbers to update an analogue voltage at uniform sampling intervals. The sequence of numbers can be written to the DAC with a clock signal that causes each number to be latched in sequence, at which time the DAC output voltage changes from a previous value to a value represented by the currently latched number. The output voltage is held in time at the current value until the next input number is latched resulting in a piecewise constant shaped output. The piecewise constant shaped output or rectangular pulses can cause multiple harmonics above the Nyquist frequency, which can be removed with a reconstruction filter.
Other conventional DAC architectures, such as DAC methods based on Delta-sigma modulation produce a pulse-density modulated signal that can then be filtered to produce a smoothly varying signal.
These conventional DAC architectures typically are implemented as analog circuits and thus can consume a significant amount of current and silicon area, making such conventional DAC architectures unsuitable for some applications where a low cost DAC architecture is desired.